the default forum permissions for the newly registered user group are all no.
however, you have to set the newly registered user group as default for it to work.
if you want the members of that group to have their first post moderated then you have to set that to yes and choose the number of posts as you have done already.
the default forum permissions for the registered user group for posting are yes and posting without approval is yes.
not sure where you went astray with your permission settings.
also, once you have created a forum with the permissions set the way you wish, you can simply copy those permissions to each new forum that you want to have those same permissions. there is a drop down on the page when creating a new forum for this.
you can create a new forum with different permission settings and copy those permissions to any new forum you want to have those permssions as well.
this may help:
https://www.phpbb.com/support/docs/en/3 ... rmissions/
Knowledge Base - phpBB3 Permissions